Active Ethernet Cable With Preset Pre-Equalization
Patent No. US10877233 (titled "Active Ethernet Cable With Preset Pre-Equalization") was filed by Credo Technology Group Ltd on Nov 27, 2019.
What is this patent about?
’233 is related to the field of high-speed data communication cables, specifically active cables used in data centers and networking equipment. These cables are designed to transmit data at rates of 50 Gbps and beyond over copper conductors. The challenge in this field is to maintain signal integrity and minimize signal degradation (attenuation and dispersion) over longer cable lengths, while keeping costs down compared to active optical cables (AOCs).
The underlying idea behind ’233 is to incorporate data recovery and remodulation (DRR) chips within the cable connectors at each end of the cable. These chips perform clock and data recovery (CDR) and then re-transmit the signal. Crucially, the DRR devices apply pre-equalization to the electrical signals transmitted over the cable's conductors. This pre-equalization compensates for signal distortion introduced by the cable itself, reducing the need for complex equalization at the receiver and improving overall signal quality.
The claims of ’233 focus on a cable assembly comprising DRR devices at each end, electrical conductors connecting the DRR devices, and the DRR devices performing pre-equalization using transmit filter coefficient values stored in nonvolatile memory. The claims also cover a manufacturing method for such a cable, and a communications method using the cable.
In practice, the cable functions as follows: data enters the cable through a connector, is received by a DRR device, which recovers the clock and data, applies pre-equalization based on stored filter coefficients, and then re-transmits the signal over the cable's conductors. At the other end, another DRR device receives the signal, recovers the clock and data, and sends the data to the host device. The pre-set transmit-side equalization is key to ensuring robust performance.
This approach differs from traditional passive copper cables, which rely solely on receiver-side equalization to compensate for signal degradation. It also differs from active optical cables (AOCs) by using copper conductors instead of optical fibers, offering a more cost-effective solution for shorter distances. By incorporating DRR and pre-equalization, the cable can achieve higher data rates and longer reach than passive copper cables, while remaining more affordable than AOCs. The use of nonvolatile memory to store the pre-equalization parameters allows the cable to be pre-configured for optimal performance.
How does this patent fit in bigger picture?
Technical landscape at the time
In the late 2010s when ’233 was filed, active cables were becoming more prevalent in data centers at a time when systems commonly relied on electrical-to-optical conversion for longer distances. At that time, increasing data rates made signal integrity and power consumption non-trivial problems, especially when hardware or software constraints made equalization at the receiver complex. It was a common practice to use passive copper cables for short distances, but attenuation and dispersion limited their use as data rates increased.
Novelty and Inventive Step
The examiner approved the application because the prior art did not teach or suggest first and second data recovery and re-modulation (DRR) devices providing pre-equalization of electrical transit signals using transmit filter coefficient values stored in nonvolatile memories. This was the key feature in the claimed combination of independent claims 1, 8, and 15.
Claims
This patent contains 20 claims, with independent claims 1, 8, and 15. Independent claim 1 focuses on a cable with data recovery and re-modulation devices at each end, claim 8 focuses on a cable manufacturing method, and claim 15 focuses on a communications method using the cable. The dependent claims generally elaborate on specific features, components, or steps related to the cable, manufacturing method, and communications method described in the independent claims.
Key Claim Terms New
Definitions of key terms used in the patent claims.
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Date
Description
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US10877233
- Application Number
- US16698935
- Filing Date
- Nov 27, 2019
- Status
- Granted
- Expiry Date
- Nov 27, 2039
- External Links
- Slate, USPTO, Google Patents